Why was lead added to petrol?
Petrol needs a certain octane level to prevent the engine from “pinging” or “knocking”. Engine knock is caused by the uncontrolled detonation of the last part of the air-fuel mixture in the combustion chamber and may damage the engine. The octane rating of a fuel is a measure of its resistance to knock – the higher the rating, the less will be the tendency of a fuel to cause knock. Adding lead compounds to petrol was the most cost-effective way of boosting its octane rating.
